Car exhaust

Recently my friend sent her car in for a new engine. She just got the car back and is saying she can smell car exhaust coming through the air like they hooked something up wrong so I told her to go back and have then fix it when they said no fumes were there. She smells like fumes as well so not sure what to do in this situation

sometimes oil would be spilled on the exhaust and it can take a few days to burn and vent, but if smell keeps coming, it definitely needs to be checked